Defer loading of Tag.Annotation and Tag.Target properties

LibGit2Sharp.Tests/TagFixture.cs

@@ -10,7 +10,7 @@ namespace LibGit2Sharp.Tests
     [TestFixture]
     public class TagFixture : BaseFixture
     {
-        private readonly List<string> expectedTags = new List<string> {"test", "e90810b", "lw"};
+        private readonly List<string> expectedTags = new List<string> { "test", "e90810b", "lw" };
 
         private static readonly Signature signatureTim = new Signature("Tim Clem", "timothy.clem@gmail.com", DateTimeOffset.UtcNow);
         private static readonly Signature signatureNtk = new Signature("nulltoken", "emeric.fermas@gmail.com", Epoch.ToDateTimeOffset(1300557894, 60));
@@ -76,12 +76,15 @@ public void CanCreateATagWithNameContainingASlash()
                 var lwTag = repo.Tags.Create(lwTagName, commitE90810BSha);
                 lwTag.ShouldNotBeNull();
                 lwTag.IsAnnotated.ShouldBeFalse();
+                lwTag.Target.Sha.ShouldEqual(commitE90810BSha);
                 lwTag.Name.ShouldEqual(lwTagName);
 
                 const string anTagName = lwTagName + "_as_well";
                 var anTag = repo.Tags.Create(anTagName, commitE90810BSha, signatureNtk, "a nice message");
                 anTag.ShouldNotBeNull();
                 anTag.IsAnnotated.ShouldBeTrue();
+                anTag.Target.Sha.ShouldEqual(commitE90810BSha);
+                anTag.Annotation.Target.ShouldEqual(anTag.Target);
                 anTag.Name.ShouldEqual(anTagName);
             }
         }
@@ -158,9 +161,10 @@ public void CreatingAnAnnotatedTagIsDeterministic()
             using (var repo = new Repository(path.RepositoryPath))
             {
                 var newTag = repo.Tags.Create(tagName, commitE90810BSha, signatureNtk, tagMessage);
-                newTag.Target.Sha.ShouldEqual("24f6de34a108d931c6056fc4687637fe36c6bd6b");
+                newTag.Target.Sha.ShouldEqual(commitE90810BSha);
                 newTag.IsAnnotated.ShouldBeTrue();
                 newTag.Annotation.Sha.ShouldEqual("24f6de34a108d931c6056fc4687637fe36c6bd6b");
+                newTag.Annotation.Target.Sha.ShouldEqual(commitE90810BSha);
             }
         }
 
@@ -284,7 +288,7 @@ public void CanCreateATagPointingToATree()
             using (var path = new TemporaryCloneOfTestRepo())
             using (var repo = new Repository(path.RepositoryPath))
             {
-                var headCommit = (Commit)repo.Head.Tip;
+                var headCommit = repo.Head.Tip;
                 var tree = headCommit.Tree;
 
                 var tag = repo.ApplyTag("tree-tag", tree.Sha);
@@ -328,10 +332,10 @@ public void CreatingALightweightTagPointingToATagAnnotationGeneratesAnAnnotatedT
                 var tag = repo.ApplyTag("lightweight-tag", annotation.Sha);
                 tag.ShouldNotBeNull();
                 tag.IsAnnotated.ShouldBeTrue();
-                tag.Target.Id.ShouldEqual(annotation.Id);
+                tag.Target.Id.ShouldEqual(annotation.Target.Id);
                 tag.Annotation.ShouldEqual(annotation);
 
-                repo.Lookup(tag.Target.Id).ShouldEqual(annotation);
+                repo.Lookup(tag.Annotation.Id).ShouldEqual(annotation);
                 repo.Tags[tag.Name].ShouldEqual(tag);
             }
         }
@@ -348,10 +352,9 @@ public void CanCreateAnAnnotatedTagPointingToATagAnnotation()
                 var tag = repo.ApplyTag("annotatedtag-tag", annotation.Sha, signatureNtk, "A new annotation");
                 tag.ShouldNotBeNull();
                 tag.IsAnnotated.ShouldBeTrue();
-                tag.Annotation.TargetId.ShouldEqual(annotation.Id);
+                tag.Annotation.Target.Id.ShouldEqual(annotation.Id);
                 tag.Annotation.ShouldNotEqual(annotation);
 
-                repo.Lookup(tag.Target.Id).ShouldEqual(tag.Annotation);
                 repo.Tags[tag.Name].ShouldEqual(tag);
             }
         }
@@ -597,15 +600,15 @@ public void CanLookupAnAnnotatedTag()
                 var tag = repo.Tags["e90810b"];
                 tag.ShouldNotBeNull();
                 tag.Name.ShouldEqual("e90810b");
-                tag.Target.Sha.ShouldEqual(tagE90810BSha);
+                tag.Target.Sha.ShouldEqual(commitE90810BSha);
 
                 tag.IsAnnotated.ShouldBeTrue();
                 tag.Annotation.Sha.ShouldEqual(tagE90810BSha);
                 tag.Annotation.Tagger.Email.ShouldEqual("tanoku@gmail.com");
                 tag.Annotation.Tagger.Name.ShouldEqual("Vicent Marti");
                 tag.Annotation.Tagger.When.ShouldEqual(DateTimeOffset.Parse("2010-08-12 03:59:17 +0200"));
                 tag.Annotation.Message.ShouldEqual("This is a very simple tag.\n");
-                tag.Annotation.TargetId.Sha.ShouldEqual(commitE90810BSha);
+                tag.Annotation.Target.Sha.ShouldEqual(commitE90810BSha);
             }
         }
 

LibGit2Sharp/CommitCollection.cs

@@ -315,7 +315,7 @@ private ObjectId DereferenceToCommit(string identifier)
 
                 if (obj is TagAnnotation)
                 {
-                    return DereferenceToCommit(((TagAnnotation)obj).TargetId.Sha);
+                    return DereferenceToCommit(((TagAnnotation)obj).Target.Sha);
                 }
 
                 throw new InvalidOperationException();
@@ -343,7 +343,7 @@ private IEnumerable<ObjectId> RetrieveCommitOids(object identifier)
 
                 if (identifier is TagAnnotation)
                 {
-                    yield return DereferenceToCommit(((TagAnnotation)identifier).TargetId.Sha);
+                    yield return DereferenceToCommit(((TagAnnotation)identifier).Target.Id.Sha);
                     yield break;
                 }
 

LibGit2Sharp/GitObject.cs

@@ -56,7 +56,7 @@ internal static GitObject CreateFromPtr(IntPtr obj, ObjectId id, Repository repo
                     case GitObjectType.Tree:
                         return Tree.BuildFromPtr(obj, id, repo);
                     case GitObjectType.Tag:
-                        return TagAnnotation.BuildFromPtr(obj, id);
+                        return TagAnnotation.BuildFromPtr(obj, id, repo);
                     case GitObjectType.Blob:
                         return Blob.BuildFromPtr(obj, id, repo);
                     default:

LibGit2Sharp/Reference.cs

@@ -74,8 +74,7 @@ public abstract class Reference : IEquatable<Reference>
 
             if (Equals(typeof(T), typeof(Tag)))
             {
-                GitObject targetGitObject = repo.Lookup(targetIdentifier);
-                return new Tag(reference.CanonicalName, targetGitObject, targetGitObject as TagAnnotation) as T;
+                return new Tag(reference.CanonicalName, targetOid, repo) as T;
             }
 
             if (Equals(typeof(T), typeof(Branch)))

LibGit2Sharp/Tag.cs

@@ -11,21 +11,23 @@ public class Tag : IEquatable<Tag>
         private static readonly LambdaEqualityHelper<Tag> equalityHelper =
            new LambdaEqualityHelper<Tag>(new Func<Tag, object>[] { x => x.CanonicalName, x => x.Target });
 
-        internal Tag(string canonicalName, GitObject target, TagAnnotation tagAnnotation)
+        private readonly Lazy<GitObject> targetBuilder;
+
+        internal Tag(string canonicalName, ObjectId targetId, Repository repo)
         {
             Ensure.ArgumentNotNullOrEmptyString(canonicalName, "canonicalName");
-            Ensure.ArgumentNotNull(target, "target");
+            Ensure.ArgumentNotNull(targetId, "targetId");
+            Ensure.ArgumentNotNull(repo, "repo");
 
             CanonicalName = canonicalName;
-            Target = target;
-            Annotation = tagAnnotation;
+            targetBuilder = new Lazy<GitObject>(() => repo.Lookup<GitObject>(targetId));
         }
 
         /// <summary>
         ///   Gets the optional information associated to this tag.
         /// <para>When the <see cref="Tag"/> is a lightweight tag, <c>null</c> is returned.</para>
         /// </summary>
-        public TagAnnotation Annotation { get; private set; }
+        public TagAnnotation Annotation { get { return targetBuilder.Value as TagAnnotation; } }
 
         /// <summary>
         ///   Gets the full name of this branch.
@@ -40,7 +42,19 @@ internal Tag(string canonicalName, GitObject target, TagAnnotation tagAnnotation
         /// <summary>
         ///   Gets the <see cref="GitObject"/> that this tag points to.
         /// </summary>
-        public GitObject Target { get; private set; }
+        public GitObject Target {
+            get
+            {
+                var target = targetBuilder.Value;
+
+                if ((!(target is TagAnnotation)))
+                {
+                    return target;
+                }
+
+                return ((TagAnnotation)target).Target;
+            }
+        }
 
         /// <summary>
         ///   Indicates whether the tag holds any metadata.

LibGit2Sharp/TagAnnotation.cs

@@ -9,6 +9,8 @@ namespace LibGit2Sharp
     /// </summary>
     public class TagAnnotation : GitObject
     {
+        private Lazy<GitObject> targetBuilder;
+
         internal TagAnnotation(ObjectId id)
             : base(id)
         {
@@ -25,16 +27,16 @@ internal TagAnnotation(ObjectId id)
         public string Message { get; private set; }
 
         /// <summary>
-        ///   Gets the target id that this tag points to.
+        ///   Gets the <see cref="GitObject"/> that this tag annotation points to.
         /// </summary>
-        public ObjectId TargetId { get; private set; }
+        public GitObject Target { get { return targetBuilder.Value; } }
 
         /// <summary>
         ///   Gets the tagger.
         /// </summary>
         public Signature Tagger { get; private set; }
 
-        internal static TagAnnotation BuildFromPtr(IntPtr obj, ObjectId id)
+        internal static TagAnnotation BuildFromPtr(IntPtr obj, ObjectId id, Repository repo)
         {
             var oidPtr = NativeMethods.git_tag_target_oid(obj);
             var oid = (GitOid)Marshal.PtrToStructure(oidPtr, typeof(GitOid));
@@ -44,7 +46,7 @@ internal static TagAnnotation BuildFromPtr(IntPtr obj, ObjectId id)
                            Message = NativeMethods.git_tag_message(obj).MarshallAsString(),
                            Name = NativeMethods.git_tag_name(obj).MarshallAsString(),
                            Tagger = new Signature(NativeMethods.git_tag_tagger(obj)),
-                           TargetId = new ObjectId(oid)
+                           targetBuilder = new Lazy<GitObject>(() => repo.Lookup<GitObject>(new ObjectId(oid)))
                        };
         }
     }